Shippers of bulky fragile products such as glass containing windows and doors have long been hampered by the unavailability of an effective shock absorbing dunnage material that is readily available or simple to fabricate, easy to use, relatively inexpensive and readily disposable for one-way shipping. This need has been particularly acute for those shipping their products by railroad car, where the operative nature of the train during starting, stopping and car-coupling operations subjects the railroad car to high impact forces and its load to extreme shift-inducing forces during such operations. Such loads are also continuously subjected to smaller shift-inducing and impact forces during normal traveling movement of the railroad car when it rocks as a result of encountering uneven railroad tracks, and when rolling over gaps or switching voids in the railroad tracks.
To minimize damage to the railroad car load, it has been a common practice to pack the contents of the car as tightly as possible, filling in any voids and empty portions between the contents being shipped, to prevent shifting of the entire load and relative movement of the individual pieces or cartons of the load as the railroad car is subjected to the impact and normal travel jostling forces. While a number of various dunnage materials, both raw materials and of the manufactured variety, have been used for such purposes, they have generally been unacceptable as universal dunnage devices for a number of different reasons.
For example, it is advantageous for a manufacturer to dispose of the waste products of his plant such as paper products, wood products, fabrics, etc. for dunnage purposes. Direct use of such waste materials for dunnage purposes has generally proved to be impractical. While it has long been known that sawdust and wood shavings provide excellent shock absorption dunnage material properties, it is generally unworkable or impractical to shovel or blow such materials into a railroad car during loading thereof so as to fill the voids, and provides an unmanageable environmental mess and safety hazard during unloading of the car. Further, it has been found that the wood shavings or sawdust when so used as a loose dunnage material, have a tendency to settle due to vibration and impact shocks during motion of the car, which again leaves damaging voids within the railroad car. Fabric waste by-products are generally not available in the quantities needed for high volume railroad car shipping, and do not typically have the shock absorbent properties required for such purposes unless very tightly packed. Such tight packing creates an unmanageable car-loading situation. Similarly, paper waste products in, for example, shredded or crumpled form, have been generally unacceptable as effective or practical dunnage materials, for reasons already stated with respect to usage of the sawdust and fabric products.
Many shippers have resorted to filling railroad car voids with layers or corrugations of cardboard. While this method has met with limited success, it is often very difficult if not impossible to completely fill the voids within the railroad car with the cardboard to that extent required to ensure non-movement and cushioning of the load. Also, when the physical make-up of the carton sizes of a load vary from car to car, so do the dunnage size requirements for the cardboard, thus requiring time-consuming fitting and cutting operations by the packers. Further, when heavy loads are involved, the cushioning and shock absorption qualities of the cardboard offers limited protection against the large impact forces involved during shipment. Other disadvantages for the use of cardboard include potentially significant costs to the manufacturer, of the general inability to re-use the cardboard for subsequent packing operations at the receiving terminal, and disposal of the cardboard at the receiving terminal.
In an effort to overcome such above-described disadvantages of raw or waste materials when used directly for dunnage purposes, a number of manufactured dunnage devices have been introduced. Such dunnage devices can be generally divided into two groups: (1) pneumatic shock absorption devices; and (2) particulate shock absorption material containing devices.
Examples of the pneumatic dunnage devices are disclosed by Miller U.S. Pat. No. 3,987,736 and Feldkamp U.S. Pat. No. 3,199,689. The pneumatic dunnage devices are basically inflatable balloons or bags that provide cushioning upon impact. Since such devices depend entirely for their cushioning ability upon the air-tight nature of the pneumatic portion of the device, it is important for such devices to include a protective external structure for shielding the inflatable member from puncture. Such construction increases both the complexity and cost of the device and makes it generally impractical as a disposable item for one-way shipping requirements.
Typical of the particulate shock absorption material containing dunnage devices are those described by La Rocca et al U.S. Pat. No. 3,515,267, by Heider et al U.S. Pat. No. 3,462,007 and by Spertus et al U.S. Pat. No. 3,606,726. The dunnage devices described by these patents generally comprise an outer envelope housing a shock absorbing particulate material. In the devices described by La Rocca and Heider, the filler material comprises a bead-like manufactured material such as polystyrene, vinyl, foam rubber or the like. Since such materials are generally expensive when used in significant quantities, the cost of such dunnage devices makes such devices generally impractical as disposable one-time-use items. Spertus et al discloses a dunnage device that uses waste products readily available to the manufacturer for the dunnage device filler material. The bag housing the filler material is perforated to allow free flow of air through the bag when subjected to an impact force. The dunnage device described by Spertus offers significant cost advantages to a manufacturer over such devices which require manufactured or purchased filler material. However, when used with particulate filler materials having a relatively high moisture content, the filler material within a dunnage device such as described by Spertus may freeze in subzero temperatures, rendering the device ineffective as a shock absorption device.
The present invention offers an improved dunnage device that fills a need in the art for a simple, effective, inexpensive, easy to use and readily disposable or, alternatively, re-usable dunnage device, the use of which is not limited by extreme temperature variations.